Electric furnace.



No. 685,717. Patented Oct. 29, I901.

0. FRDLICH.

ELECTRIC FURNACE.

(Application filed Sept. 27, 1898.)

(No Model.)

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Oscar Frd/z ch,

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THE NORRIS vrrzns co, Pnowouma, WASHINGTON, n. c.

NrrsD STATES PATENT OFFros.

OSCAR FROLIOH, OF STEGLITZ, NEAR BERLIN, GERINIANY,.ASSIGNOR TO THE FIRMOF SIEMENS & HALSKE AKTIEN-GESELLSOHAFT, OF BERLIN,

GERMANY.

ELECTRIC FURNACE.

. SPECIFIGATION forming part of Letters Patent N 0. 685,717, datedOctober 29, 1901.

Application filed September 27,1898. Serial No. 691,974. (No model.)

To ctZZ whom it may concern.-

Be it known that I, OSCAR FRoLIcH, a citizen of the Swiss Republic,residing at Steglitz, near Berlin, German Empire, have invented acertain new and useful Improvement in Electric Furnaces, (Case No. 1,)of which the following is a full, clear, concise, and exact description.

My invention relates to electric furnaces preferably for the productionof carbid of calcium.

The invention consists in employing in such furnaces a tube-shapedelectrode which passes through a layer of pulverized material by meansof which its interior is hermetically separated from theatmospheric'air.

Of the accompanying drawings, Figure lis a Vertical section showing thearrangement of my furnace, and Fig. 2 is a horizontal section on line ab in Fig. 1.

O is an iron box or crucible lined inside with a thick layer ofrefractory bricks in 'order to make it fireproof and having a bottomshaped like an inverted cone or pyramid and provided with an opening Oin the center thereof,which serves for tapping off the products of thereaction. I I

D is a table likewise preferably made of iron and lined with refractorycarbon and being shaped like an upright cone or pyramid with the pointout off. The table D is supported by a central prop or pillar A, whichcan be raised or lowered by means of the le-- ver L, so as to eitherclose or open the open ing 0 in the crucible O.

K is a tube madeof carbon and serving as the one electrode, the interiordiameter of said tube being so dimensioned as to be not appreciablysmaller than the opening 0 in the bottom of the crucible. The carbon Kis suspended from an iron rod B and can be raised or lowered by means ofthe latter, so as to regulate the length of the are.

The tube-shaped carbon K is hermetically closed at the top by means ofthe lid E, and a suitable number of flexible pipes M M are inserted insaid lid which lead to a gas-fun nace R, fitted below the crucible O.Air-inlets P are provided in the sides of R to allow the combustion ofthe gas that is admitted by'the tubes M M. The furnace R is alsoprovided with a suitable flue S, adapted to carry off the products ofcombustion.

My electric furnace is preferably adapted for the production of carbidof calcium and is operated as follows: It is known that when carbon andlime are allowed to react upon one another in the electric furnace notonly earbid of calcium is formed, but also a part of the carbon combineswith the oxygen of the lime and forms monoxid of carbon. The latter gasgenerally is allowed to make its way through the raw material that isheaped up around the upper carbon of the furnace and frequently createsserious difficulties bycausing sudden and sometimes violent-eruptions,which form flames as soon as the hot gas comes into contact with the airat the surface or in the interior of the material. By such flamesthesurface of the upper carbon is seriously injured, and consequentlyits durability much impaired. It is the object of my invention toovercome these difiiculties bycarrying ed the monoxid gas in an unburnedstate from the reaction and leading it to a place where the heat causedby its combustion can be usefully employed for promotingthe operation ofthe furnace or for other purposes. If the upper carbon of an electricfurnace is made hollow, the gases produced by the reaction going on inthe are do not voluntarily escape through the interior of the tube,because they preferably form at the outer lower edge of the latter andthere would find a more easy exit along the outside of the tube if nomeans were provided to prevent them from freely escaping. Now I havefound that if the raw material that is to be subjected to the action ofthe arc-t. 6., in the case of calcium carbid the mixture of carbon andlimeis pulverized to a sufficient fineness and heaped up about theexterior of the tube-shaped carbon it will form a perfectly gas-tightinclosure around the are, thus compelling the monoxid of carbon formedin the latter to take its way through the interior of the tube-shapedcarbon. By this simple means a double advantage is obtainednamely, thatthe disturbing eruptions of the gas are totally avoided, and, secondly,that no air is admitted to the arc, the result being that theconsumption of the carbon electrode is considerably diminished. WVhen asufficient quantity of carbid has been formed, the table D can belowered and the prod uct,which forms itself in the furnace in a liquidor solid state, can be allowed to run off or to be taken away by irontools. If it should not appear essential to save all the heat obtainablefrom the material that is being operated upon, the tube K can be crownedby a number of vertical tubes of such dimensions that the flames burningat the top of these tubes cannot descend into the interior of the largetube K. However, ordinarily I prefer to lead it into the furnace R bymeans of flexible tubes MM and by burning it under the crucible O toheat the latter and the material therein, and thus save electricalenergy which would othcrwise be consumed in raising the tempera ture ofthe raw material that is continuously being fed into the are. It will beseen that though by the herein-described arrangement the air isperfectly excluded from the arc, nevertheless the upper carbon remainsaccessible, and, What is of still greater importance, the crucible canbe refilled continuously without interrupting theoperatiou.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is 1. In an electric furnace, the combination with acrucible forming one electrode, of a centrally-disposed tubular carbonelectrode movably mounted within said crucible between the side walls ofwhich and the said electrode the material to be treated is packed tosurround the lower portion of said electrode and form a gas-tightenvelop therefor, and an opening in the bottom of the crucible normallyclosed by a movable part, said opening being approximately the same sizeas the bore of the tubular electrode, substantially as described.

2. In an electric furnace, the combination with a crucible, of a carbonelectrode having a bore extending lengthwise through the same, and meansfor directing generated gas through the hollow electrode to a point nearthe exterior of the crucible where the gas may be burned to furnish heatfor the operation of the crucible, substantially as described.

3. In an electric furnace, the combination with a crucible forming oneelectrode, of a tubular carbon electrode movably mounted therein andextending approximately to the bottom of said crucible, the said furnacebe ing constructed to provide a free space be tween the side walls ofthe crucible and carbon electrode, wherein the material to be treated isdisposed to form a gas-tight envelop adapting the furnace for continuousoperation, a tube or tubes leading from the bore of the tubularelectrode, a gas-furnace connected therewith, and a normally closedopening in the bottom of the crucible through which the furnace productis removed, substantially as described.

4. In an electric furnace preferably for the production of carbid ofcalcium the combination with a crucible having a central opening at thebottom a centrally-introduced movable tube-shaped upper carbon the saidcrucible being adapted to be filled with pulverized raw material to sucha height as to exclude the air from the arc of a lid hermeticallyclosing the upper end of said tube-shaped carbon and containing pipesadapted to carry off the gaseous prod uets issuing from the are, saidpipes leading to a gas-furnace arranged below said cruciblesubstantially as and for the purpose described.

In witness whereof I have hereunto subscribed my name this 6th day ofSeptember,

OSCAR FROLIOII. 'Witnesses:

O. H. DAY, HENRY HASPER.

